Dot| Lewis structure of Chromic Acid H2CrO4 - #50

A simple procedure for writing Lewis Structures was given in a previous article entitled “Lewis Structures and the Octet Rule”.
Several worked examples relevant to this procedure were given in previous posts please see the Sitemap - Table of Contents (Lewis Electron Dot Structures).

Let us consider the case of chromic acid. The chemical formula is H₂CrO₄.

Step 1: Connect the atoms with single bonds. 

Fig. 1:  The H₂CrO₄ atoms connected with single bonds

Step 2:  Calculate the # of electrons in π bonds (multiple bonds) using  formula (1):

Where n in this case is 5, excluding the H atoms. Where V = (1 + 6 + 6 + 6+ 6 + 6 + 1) = 32 , V is the number of valence electrons of the molecule.

Therefore, P = 6n + 2 – V = 6 * 5 + 2 – 32  = 0     So, there is no multiple bond in the molecule.

Step 3 & 4: The  resonance structures of H₂CrO₄  are as follows:

Fig. 2:  Lewis electron dot structure of H₂CrO₄